The present invention relates to an optical information writing-reading apparatus, and in particular to an optical disk apparatus. However, the present invention can be applied to general apparatuses using an optical servo function in which tracking control is exercised by using an optical signal.
As a background art, there is a technique disclosed in JP-A-2006-294189. “PROBLEM TO BE SOLVED” is described in JP-A-2006-294189 to be “to provide a tracking control method of an optical disk device capable of correcting off-set of a tracking error signal with high precision even when there are nonlinear characteristics e.g. wherein a shift amount of a position of an objective lens to a mechanically neutral position of the objective lens and an off-set amount of the tracking error signal are not proportional to each other, and to provide the optical disk device.” As SOLUTION, there is description “In the tracking control method of the optical disk device performing control by using the tracking error signal, an optical pickup 4 is provided with the objective lens, the shift amount of the position of the objective lens to the mechanically neutral position of the objective lens is estimated and a correction signal of the tracking error signal is generated according to the estimated shift amount of the position of the objective lens by using any one of a plurality of correction functions.”